The use of microscopic active agent delivery systems such as those comprising microcapsules, microparticles and liposomes is known.
For example, International Patent application No. WO 2006/007372 describes a particulate delivery system comprising an extracted yeast cell wall comprising beta-glucan, a payload molecule and a payload trapping molecule.
In addition, International Patent application No. WO 2005/113128 describes compositions comprising a hollow glucan particles or hollow cell wall particles encapsulating an effective amount of a terpene component which are suitable for preventing and treating infections in plants and animals, including humans, said compositions comprising 1 to 99% by volume terpenes.
Furthermore, it is known to include preservatives in such compositions, for example methyl hydroxybenzoate, ascorbic acid and sorbic acid.
Anti-mycotic materials are often added to foods to extend the usable life span of the foods to inhibit the growth of moulds, yeasts, fungi, etc.
Certain microparticle compositions comprise perishable materials, such as yeast or glucan particles. Such compositions are susceptible to degradation or spoilage by mould, yeast, or fungal growth. The usable life span of the microparticles can be drastically reduced due to spoilage by mould, yeast, or fungal growth.
It has now been surprisingly found that the inclusion in a microparticle composition of an amount of one or more terpenes, below the conventionally understood effective level, may provide a useful preservative effect on the microparticle.